NDEF NFC Forum Spec
NDEF message and NDEF record NDEF 는 NFC Forum Data Exchange Format 의약자로서가벼운바이너리메시지포맷을지향하며하나이상의애플리케이션에서정의한 PAYLOAD 들을하나의메시지구조에캡슐화하여정의 하나의 NDEF 메시지는하나이상의 NDEF record 들을가지고있으며임의의타입의 PAYLOAD 를젂송하는데목적 NDEF record 는 Payload 에대한정보를포함 - Payload length SR bit 플래그의값이 1 인지아닌지로구분 효율적으로 record 경계를감지 - Payload type record 의 Payload 에포함되어있는데이터의종류를명시 - Payload identifier(optional) the general view of NDEF message 21
NDEF record Payload length(sr=0) Payload Type Payload identifier(optional) 22
NDEF Analysis(Hexa code)-url(http://nokia.com) 03 0e d1 01 0a 55 03 6e 6f 6b 69 61 2e 63 6f 6d fe 03 (T: Type) - Type of recode 0e (L : Lenght) - how many bytes are in the payload d1 (V : Value) - NDEF records are variable length records with a common format illustrated in the figure below. - d1 is binary code (11010001) IL 이 0 이기때문에 ID LENGTH 가 Layout 에존재하지않는다. 01 TYPE LENGTH 0a PATLOAD LENGTH 55 TYPE( U ) 03 ID(http://) - optional 6e 6f 6b 69 61 2e 63 6f 6d Payload (nokia.com) fe Terminator byte NDEF record header NDEF record header Payload 23
Record Layout (1/2) 1 1 0 1 0 0 0 1 MB ME CF SR IL TNF MB = 1 - Message Begin is true means this is first record in the NDEF message ME = 1 - Message end, means it is last record in the NDEF message, if it is 0 that tells application that more records are ahead CF = 0 - The CF flag is a 1-bit field indicating that this is either the first record chunk or a middle record chunk of a chunked payload 24
Record Layout (2/2) 1 1 0 1 0 0 0 1 MB ME CF SR IL TNF SR = 1 - SR stands for short record, if set, that the payload length field is a single octet. This short record layout is intended for compact encapsulation of small payloads which will fit within PAYLOAD fields of size ranging between 0 to 255 octets IL = 0 (ID_LENGTH Field 와연관 ) - IL stands for identification length, if set, that the ID_LENGTH field is present in the header as a single octet. If the IL flag is zero, the ID_LENGTH field is omitted from the record header and the ID field is also omitted from the record TNF = 001 - The TNF field value indicates the structure of the value of the TYPE field. The value 0x01 (NFC Forum well-known type) indicates that the TYPE field contains a value that follows the RTD type name format defined in the NFC Forum RTD specification 25
Short-Record Layout(SR = 1)(1/2) SR 플래그는 1-bit 필드 SR = 1 - PAYLOAD_LENGTH Field 는 1 octet - PAYLOAD 의길이가 0 ~ 255 octet 사이의길이가짧으면다음과같이 short record 레이아웃으로젂달 SR = 0 - PAYLOAD_LENGTH Field 는 4 octet short record 레이아웃으로할지일반 record 레이아웃으로할지는구현자가선택하는것이고 NDEF 파서는양쪽다지원해야한다. 26
Short-Record Layout(SR = 1)(2/2) NDEF Record Layout (SR=0) NDEF Short-Record Layout (SR=1) 27
TNF 필드값 (1/3) Type Name Format Empty NFC Forum well-known type [NFC RTD] RFC 2046에정의된 Media-type RFC 3986에정의된젃대 URI 경로 NFC Forum external type [NFC RTD] Unknown Unchanged Reserved Value 0x00 0x01 0x02 0x03 0x04 0x05 0x06 0x07 TNF Field 의기본값은없으며 Reserved TNF Field 값은앞으로사용하기위함이며현재는사용하지않아야한다. NDEF 파서는알수없거나지원되지않는 TNF Field 값이있는 NDEF record 를수싞하였을경우 0x05 (Unknown) 으로변경한다. 28
TNF 필드값 (2/3) 0x00 (Empty) - record 와연관된타입혹은 PAYLOAD 가없다는것을나타냄 - TYPE_LENGTH, ID_LENGTH 그리고 PAYLOAD_LENGTH Field 는 0 - TYPE, ID 그리고 PAYLOAD Field 는 record 로부터생략 - TNF 값은앱에서더이상의 PAYLOAD 가없을경우하나의 NDEF 메시지를종료한다는의미로서빈 record 가필요할때사용한다. 0x01 (NFC Forum well-known type) - TYPE Field 에 NFC 포럼 RTD 스펙에서정의한 RTD 타입이름형식을따르는값을포함하고있음을나타낸다. 0x02 (media-type) - TYPE Field 에 RFC 2046 에서정의한 media-type BNF 구조를따르는값이포함되어져있음을나타낸다. 0x03 (absolute-uri) - TYPE Field 에 RFC 3986 에서정의한 absolute-uri BNF 구조를따르는값이포함되어져있음을나타낸다. 29
TNF 필드값 (3/3) 0x04 (NFC Forum external type) - TYPE Field 에외부타입명을위한 NFC RTD 에정의한타입이름형식을따르는값을포함하고있음을나타낸다. 0x05 (Unknown) - PAYLOAD 의타입을알수없을때사용 - RFC 2046 에서정의한 MIME 중 "application/octet-stream" 과유사 - type_length Field 는 0 이고 TYPE Field 는 NDEF record 에서생략 - 구현시이값을사용하는추가컨텍스트가없이이타입의 NDEF record 를수싞하는 NDEF 파서는 PAYLOAD 를처리하지않고저장하는메커니즘을제공하는것을권고 0x06 (Unchanged) - 청크된 PAYLOAD 들을포함하고있는중갂 record 청크와마지막 record 청크에서사용 - 다른 record 의경우에는사용하지않아야한다. - TYPE_LENGTH Field 는 0 이어야하고 TYPE Field 는 NDEF record 에서생략된다. 0x07 - 앞으로어떤 Type 을나타내는값으로쓰일지는모르지맊예약된값 (Reserved) 으로정의 30
NDEF Structure(1/2) TYPE_LENGTH - TYPE_LENGTH Field 는 8-bit 부호없는정수형으로 TYPE Field 의 octet 길이를명시 - TNF 가 0x00, 0x05, 0x06 일경우항상 0 ID_LENGTH - ID_LENGTH Field 는 8-bit 부호없는정수형으로 ID Field 의 octet 길이를명시 - 오직 IL 이 1 로설정되어있을경우에맊존재 - ID_LENGTH 의값이 0 으로설정되면 ID Field 는 NDEF record 에서생략 PAYLOAD_LENGTH - PAYLOAD_LENGTH 는부호없는정수로서 PAYLOAD Field 의 octet 길이를명시 - PAYLOAD_LENGTH Field 의값길이는 SR 플래그설정에의해결정 SR 플래그가설정되어있다면 PAYLOAD_LENGTH Field 는 8-bit 부호없는정수를나타내는 1 octet SR 플래그가설정되어있지않다면 PAYLOAD_LENGTH Field 는 32-bit 부호없는정수형을나타내는 4 octet 이고 MSB-first 순으로읽는다. - PAYLOAD_LENGTH Field 값이 0 이면 PAYLOAD Field 는 NDEF record 에서생략 2^(32)-1 크기보다더큰 PAYLOAD 일경우청크된 PAYLOAD 를사용한다. 31
NDEF Structure(2/2) TYPE ID - TYPE Field 의값은 PAYLOAD 의타입을설명하는식별자이다. TYPE Field 의값은 TNF Field 값에해당하는구조, 인코딩, 형식을따라야한다. - NDEF 파서는알수없는 TYPE Field 값을나타내는 TNF Field 의 NDEF record 가수싞될경우마치 TNF Field 값이 0x05(Unknown) 인것처럼타입식별자를분석해야한다. - 타입식별자는글로벌적으로유일하고안정적으로유지되고의미가오랜시갂잘정의되어사용되는것을강력히권고한다. - ID Field 의값은 URI 형식 [RFC 3986] 의식별자이다. 유일한메시지식별자가되도록생성되어야하며 URI 는젃대혹은상대적형식일수있다. NDEF 는기본 URI 를정의하지않으며사용자앱에서상대경로형식의 URI 를사용할경우실제적이든가상적이든기본 URI 를제공해야한다. - 중갂 (middle) 혹은마지막 (terminating) record 청크들은 ID Field 를가지지않아야하며싱글혹은첫번째 (initial) record 청크에는 ID Field 가있어야한다. PAYLOAD - PAYLOAD Field 는 NDEF 사용자앱을위해 PAYLOAD 를젂달한다. PAYLOAD Field 를통해젂달되는데이터의내부적구조에대해서는 NDEF 에서정의하고있지않다. 32
RTD
Record Types Record type 의 name 은 NDEF applications 을구분하기위해서사용됨 각각의 Record Type 은 NFC Forum 과 third parties 들에의해정의됨 NDEF record header 의 TNF Field 에명시 TNF Field Values 34
NFC Forum Well-known Type Record 의 TNF field 값 0x01 [NFC Forum Well-known Type] 은매우일반적인타입들을정의하고있음 *URN 으로정의하는 NFC Forum Well-known Type 의 prefix - NID(Namespace identifier) nfc - NSS(Namespace Specific String) wkt: Detail Section - NFC Forum Global Type NFC Forum 에서정의하고관리하는부분 First - character range <upper> - NFC Forum Local Type First - character range <lower> or <number> *URN : Uniform Resource Names NFC Forum Assigned Numbers Register 35
NFC Forum External Type Record 의 TNF field 값 0x04 [NFC Forum Well-known Type] 은 third parties 에서정의하여사용 URN 으로정의하는 NFC Forum External Type 의 prefix - NID(Namespace identifier) nfc - NSS(Namespace Specific String) ext: Detail Section - third parties 에서사용하는 domain name 을추가하고 third parties 에서관리하는 Type name 을추가 - EX> urn:nfc:ext:example.com:f 36
RTD Type Names (1/2) Requirements for the NFC Forum Well-Known Type Names The language used is the ABNF format as defined in *RFC 2234 1. RTD-URI = urn:nfc: nfc-nss 2. nfc-nss = wkt-nss / external-nss 3. wkt-nss = wkt-id : WKT-type 4. external-nss = external-id : external-type 5. wkt-id = wkt 6. external-id = ext 7. WKT-type = local / global 8. local = ( lower / number ) *WKT-char 9. global = upper *WKT-char 10.external-type = dns-part : name-part 11.dns-part 12.name-part 13.WKT-char = 1*DNS-char = 1*WKT-char = upper / lower / number / other 14.DNS-char = upper / lower / number /. / - [RFC 2234] A / B == A OR B A*B(element) == A~B 회 element 를반복 (default : A = 0, B = ) *RDC 2234 : http://tools.ietf.org/html/rfc2234 37
RTD Type Names (2/2) 15.upper = A / B / C / D / E / F / G / H / I / J / K / L / M / N / O / P / Q / R / S / T / U / V / W / X / Y / Z 16.lower = a / b / c / d / e / f / g / h / i / j / k / l / m / n / o / p / q / r / s / t / u / v / w / x / y / z 17.number = 0 / 1 / 2 / 3 / 4 / 5 / 6 / 7 / 8 / 9 18.other = ( / ) / + /, / - / : / = / @ / ; / $ / _ /! / * / ' /. 19.Reserved = % / / /? / # 38
RTD Text NFC Forum Spec
NDEF Structure The NFC Forum Well Known Type [NDEF], [NFC RTD] for the Text record is T Example ( Hello ) NDEF record Header Payload 1 1 0 1 0 0 0 1 0x01 0x08 0x54 0 0 0 0 0 0 1 0 e n H e l l o 0xFE SR = 1, IL = 0, TNF = 001 TYPE LENGTH PAYLOAD LENGTH TYPE T Status byte Language Codes The actual body text Terminator byte 40
EX) Hello 0 0 0 0 0 0 1 0 0: The text is encoded in UTF-8 1: The text is encoded in UTF-16 e n *RFU The length of the language code 자리수를결정 **ISO/IANA language code H E L L O The actual body text Hello *Reserved for Future Use( 현재는사용하지않는부분으로 0 으로설정 ) **http://www.i18nguy.com/unicode/language-identifiers.html 41
RTD URI NFC Forum Spec
NDEF Structure The Well Known Type for an URI record is U URI identifier code - URI record 의 First Byte 는 protocol field 를젂달하여데이터의크기를줄인다 0x24~0xFF : RFU Abbreviation Table 43
EX) http://nokia.com NDEF record Header Payload 1 1 0 1 0 0 0 1 0x01 0x0A 0x55 0 0 0 0 0 0 1 1 N O K I A. C O M FE SR = 1, IL = 0, TNF = 001 TYPE LENGTH PAYLOAD LENGTH TYPE U URI identifier code The rest of the URI, or the entire URI Terminator byte 44
RTD Smart Poster NFC Forum Spec
NDEF Structure (1/3) The Well-known Type for the Smart Poster record type is Sp (in NFC binary encoding: 0x53, 0x70) Syntax - The URI Record (mandatory) 1 개의 URI Record 맊존재 다른 Record 들은 URI Record 의 metadata - The Title record(optional) Text RTD Record 를이용 다른언어를사용한여러개의 Record 가존재할수있음 URI 에맞는 Title 이표시될수있도록주의를요함 (Phishing) - The Icon Record(optional) 다양한 MIME 형태의 image record 포함가능 Device 의가용범위내에서이미지를표시 [PNG],[JPEG] 같은 well-known type 이용을권장 46
NDEF Structure (2/3) Syntax - continue - The Action record(optional) 어떤서비스를제공할지결정 Action record 가없는경우 Device 의추천에의해서실행 The NFC Local Type Name for the action is act (0x61 0x63 0x74). The content is a single byte Action Record Values 47
NDEF Structure (3/3) Syntax - continue - The Size Record(optional) The Size Record contains a four-byte URI 가외부독립체로연결되는경우크기를언급하는기능담당 Reader device 가 URL 등을통해읽는 content 의크기를언급해야하는경우활용 The Size Record s Local Type Name is s The Size Record Layout - The Type Record(optional) URI 가외부독립체로연결되는경우 MIME 의타입을정의 Reader device 가 URL 등을통해읽는 MIME 의타입을언급하여재생유 / 무판단 The Local Type Name for the Type Record is t 48
EX) Simple URI on a Tag NDEF record Header NDEF record Header 1 1 0 1 0 0 0 1 0x02 0x12 0x53 0x70 1 1 0 1 0 0 0 1 0x01 0x08 0x55 SR = 1, IL = 0, TNF = 001 MB = 1, ME = 1 TYPE LENGTH(2byte) PAYLOAD LENGTH(18byte) TYPE Sp SR = 1, IL = 0, TNF = 001 MB = 1, ME = 1 TYPE LENGTH(1byte) PAYLOAD LENGTH(14byte) TYPE U Payload 0 0 0 0 0 0 1 1 N O K I A. C O M FE URI identifier code The rest of the URI, or the entire URI Terminator byte 49
EX) Complex URI on a Tag (1/2) A URI with a Title and Launching a Browser NDEF record Header URI 1 1 0 1 0 0 0 1 0x02 0x12 0x53 0x70 1 0 0 0 0 0 0 1 0x01 0x00 0x00 0x00 0x0E 0x55 0 0 0 0 0 0 1 1 nfc-forum.org SR = 1, IL = 0, TNF = 001 MB = 1, ME = 1 TYPE LENGTH(2byte) PAYLOAD LENGTH(18byte) TYPE Sp SR = 0, IL = 0, TNF = 001 MB = 1, ME = 1 TYPE LENGTH(1byte) PAYLOAD LENGTH(long format) TYPE U URI identifier code the entire URI URI-act 0 0 0 1 0 0 0 1 0x03 0x01 0x61 0x63 0x74 0x00 SR = 1, IL = 0, TNF = 001 MB = 1, ME = 1 TYPE LENGTH(2byte) PAYLOAD LENGTH(18byte) TYPE act Action = Launch browser 50
EX) Complex URI on a Tag (2/2) Text(en-US) 0 0 0 1 0 0 0 1 0x01 0x12 0x54 0x05 e n - U S Hello, world SR = 1, IL = 0, TNF = 001 MB = 0, ME = 0 TYPE LENGTH(1byte) PAYLOAD LENGTH(long format) TYPE T Status byte Language Codes The actual body text Text(Finnish) 0 1 0 1 0 0 0 1 0x01 0x13 0x54 0x02 f i Morjens, maailma SR = 1, IL = 0, TNF = 001 MB = 0, ME = 1 TYPE LENGTH(1byte) PAYLOAD LENGTH(long format) TYPE T Status byte Language Codes The actual body text 51